This invention relates to devices to prevent nut and bolt assemblies from loosening over time, and in particular to securing existing flare nut unions in refrigeration systems.
Standard nut and bolt assemblies are, of course, the mainstay fasteners employed for a virtually limitless number of applications. The instant invention addresses the common problem of preventing of loosening of these unions over time, and doing so in a simple, practical manner. This disclosure particularly addresses the often encountered problem of leaking flare nut unions in refrigeration systems. Refrigerant tubing is usually connected to various components in a refrigeration system by either soldering the union together, or by use of a flare nut. Since the flare nut provides a generally reliable fluid tight union it is often preferred as the simplest means for effecting a tubing connection. By the very nature of refrigeration systems, flare nut unions are subjected to a variety of environmental conditions which tend to reverse the torquing forces originally used to effect the union, resulting in refrigeration leaks at the joint. Unfavorable environmental conditions include frequently changing extremes of temperature conditions, and vibrations from refrigeration compressors, movement of trucks and automobiles, and the like. It would therefore be desirable to be able to add a device to existing flare nut unions to either prevent future refrigerant leakage, or to insure that a field repair of a leaking flare nut union is permanent.
Attempts have been made to help prevent leaks in fluid transfer unions, and various types of nut and bolt assemblies, as is evidenced by U.S. Pat. No. 4,645,242. In this Positive Lock High Pressure Mounting a bell-flared collar and compression nut assembly securing a fluid flow measuring device within a pipe is disclosed. In the event of high pressure disengagement of the collar and compression nut, significant disengagement of the assembly is prevented by an annular rib (60) connected to the cylindrical body portion (18), and end cap (66) secured to the compression nut forming a stop for the annular rib in the event of the assembly becoming disengaged.
Again, in U.S. Pat. No. 5,350,200 a tube coupling assembly for connecting first and second fluid-carrying tubes together is disclosed. Disengagement of the assembly is prevented by a plurality of circumferentially spaced and axially extending grooves within the barrel portion of a coupling nut. Similarly, in U.S. Pat. No. 5,188,398 a redundantly locked fluid coupling is disclosed which utilizes ratcheting teeth or sawtooth teeth in a circumferential surface of a coupling nut to prevent disengagement of a fluid coupling. In U.S. Pat. No. 5,131,690 a self locking connector is disclosed which prevents disengagement between two fluid carrying tubular members by interposing a collar having longitudinal slots in its forward end between the tubing to be temporarily interconnected.
Additional coupling locking devices are disclosed in U.S. Pat. Nos. 5,127,679; 3,586,351; 1,639,407; and 1,139,671. In U.S. Pat. No. 5,127,679 a bushing with inner toothing for locking a joint together is disclosed; U.S. Pat. No. 3,586,751 teaches locking nuts on a combination taper and standard threaded tube; U.S. Pat. No. 1,639,407 describes deformable grooves within a nut and bolt combination to effect a locking union; U.S. Pat. No. 1,139,671 discloses a locking union between two pipe threads in which the threads of one compression nut eventually distort within the threads of a second compression nut, effecting a locking of the joint. While these various devices disclose useful joint securing assemblies they do not address the simple, reliable nut and bolt securing device of the instant invention, and in particular to the prevention of leaks in existing flare nut unions.
It is therefore a primary object of the invention to provide a simple, reliable nut and bolt securing device.
A further object of the invention is to provide a nut and bolt securing device to secure existing nut and bolt installations.
An additional object of the invention is to provide an addition to standard flare nut assemblies to provide for repair of existing flare nut installations so as to prevent future problems due to refrigerant leakage.
An additional object of the invention is to provide a device for securing flare nut assemblies in a manner to reduce freeze-thaw loosening of said device.